How much difference does swapping beef for chicken or lentils make?
Protein is the honest unit for a food comparison — comparing raw weight flatters low-protein foods.
Compared on: 100 g of protein consumed
Beef (beef herd)
25 kg CO₂eIncludes enteric methane, feed, land use change and processing.
Source: Poore & Nemecek (2018), Science — global meta-analysis
Lamb
20 kg CO₂eRuminant methane again, slightly lower feed conversion penalty.
Source: Poore & Nemecek (2018), Science
Chicken
5.7 kg CO₂eNo enteric methane, efficient feed conversion.
Source: Poore & Nemecek (2018), Science
Lentils and pulses
0.80 kg CO₂eNitrogen-fixing crop, no livestock stage.
Source: Poore & Nemecek (2018), Science; SU-EATABLE LIFE database
What this means
- Beef to chicken is roughly a 4× cut; beef to pulses is closer to 30×.
- Two beef meals a week swapped for pulses saves on the order of 300–400 kg CO₂e a year.
- How food is produced matters less than what it is — the worst chicken still beats the best beef.
Your own number, not an average
Averages answer the question; your own footprint tells you what to change first. The calculator takes about two minutes and needs no account.
Figures are averages drawn from public databases and peer-reviewed LCA work; see our methodology for how each factor is applied.